Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion at one end and an elongated portion forming a blade that extends outwardly from a platform coupled to the root portion at an opposite end of the turbine blade. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades typically contain an intricate maze of cooling channels forming a cooling system. The cooling channels in the blades receive air from the compressor of the turbine engine and pass the air through the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. However, centrifugal forces and air flow at boundary layers often prevent some areas of the turbine blade from being adequately cooled, which results in the formation of localized hot spots. Localized hot spots, depending on their location, can reduce the useful life of a turbine blade and can damage a turbine blade to an extent necessitating replacement of the blade.
Typically, conventional turbine blades have a plurality of core print out holes at the tip of the blade that are a result of the manufacturing processes commonly used to create a turbine blade. These core print out holes are often welded closed, and a plurality of exhaust orifices are drilled into the pressure and suction sides of a tip section of a turbine blade, as shown in FIGS. 1 and 2, to provide film cooling to the tip region of the turbine blade. The process of welding the core print out holes closed and drilling holes into the blade tips is time consuming and thus, costly. Thus, a need exists for a more efficient manner of manufacturing and cooling a tip of a turbine blade.
In addition, exhaust orifices proximate to a tip of a turbine blade are typically drilled into the outer housing of the turbine blade. Thus, the exhaust orifices are typically straight, which results in the cooling flow distribution and pressure ratio across these cooling holes being dictated by the internal configuration of the cooling system and not the exhaust orifices. The direction and velocity of the fluid flowing through the cooling holes cannot be regulated. Thus, a tip cooling system is needed that enables the cooling flow distribution and velocity of the cooling fluids to be regulated.